This invention relates to a method of making demineralized bone particles useful in, or as, implants having a variety of orthopedic applications. More particularly, this invention relates to a method of making particles from demineralized bone that results in a greater yield of demineralized bone particles than that provided by prior art methods of producing such particles.
The manufacture of demineralized bone particles and compositions, materials and devices containing demineralized bone particles and their use in the repair of bone defects and for other orthopedic applications are known.
The microstructure of cortical bone consists of bundles, or fibers, of mineralized collagen that are oriented parallel to the long axis of the known methods for making demineralized bone particles involve subdividing sections of whole, i.e., mineralized, bone, e.g., by such mechanical operations as shredding, milling, shaving, machining, etc., to provide particles which are then demineralized, e.g., by treatment with acid. The resulting demineralized bone particles exhibit osteoinductive properties that make them useful as, or in, implants intended for use in bone repair and other orthopedic applications. One drawback of known methods of making demineralized bone particles is that only a portion of the bone stock, e.g., 45-65% by weight, will yield demineralized bone particles. In addition, because of the mechanical limitations of the bone milling machinery, e.g., the need to grip the bone stock in the jaws of the machine, only donor bone of a fairly substantial size, e.g., intact cortical shafts, can be used as to the source of the demineralized bone particles.
The limited amount of demineralized bone particles that is obtained by the prior art methods is of concern due to the limited availability of donor bone. At this time, regulations do not permit the pooling of donor bone material. Since the quantity of demineralized bone particles that can be obtained is limited both by the availability of donor bone and the size of the bone, there is a need for a method of making demineralized bone particles that is not subject to the constraints imposed by these limiting factors.